Respiring biological materials, like fresh fruits and vegetables, consume oxygen (O2) and produce carbon dioxide (CO2). Respiration can be slowed, and freshness extended, by freezing or refrigeration. Unfortunately, maintaining the desired low temperatures is energy intensive and costly, and can adversely affect flavor and appearance. Freshness can also be extended by controlling the relative and absolute concentrations of oxygen and carbon dioxide in the packaging atmosphere surrounding the materials. Too much oxygen results in rapid spoilage, and too little can allows potentially dangerous anaerobic bacteria to thrive.
Controlled atmosphere packaging (CAP) and modified atmosphere packaging (MAP) are technologies that afford some control over the concentrations of oxygen and carbon dioxide. The preferred packaging atmosphere depends on the stored material. For example, broccoli is best stored in an atmosphere containing between one and two percent oxygen and between five and ten percent carbon dioxide, whereas raspberries benefit from a higher concentration of carbon dioxide that delays grey mold decay. There is therefore a need for packaging solutions tailored to their contents.